HIV-2 Infection

Background

• HIV-2 is an immunosuppressive virus that causes a clinical syndrome similar to HIV-1, but is considerably less common.
  • Compared to HIV-1 infection, HIV-2 infection has a longer asymptomatic stage, lower plasma virus loads, and lower mortality.
  • Progression to AIDS does occur and like patients with HIV-1 infection, patients with HIV-2 infection are at risk for opportunistic infections.
• HIV-2 is endemic in West Africa and a spread beyond this region is limited.
• HIV-1 and HIV-2 have common modes of transmission. Both may be transmitted sexually, congenitally, or via bloodborne exposure such as an occupational needlestick or recreational needle sharing.
• Co-infection with HIV-1 and HIV-2 occurs rarely. Dual infection has similar mortality to HIV-1 infection and greater mortality than HIV-2 monoinfection.

Evaluation

• Consider the diagnosis of HIV-2 infection in patients with risk factors for HIV or a clinical syndrome suggestive of HIV infection, particularly in patients from West Africa or in patients who have had sexual contact with or bloodborne exposure with a person from this region.
• Atypical HIV-1 testing results should also raise suspicion for HIV-2 infection and include either:
  • a positive screening assay with an indeterminate HIV-1 Western blot
  • serologically confirmed HIV infection but low or undetectable HIV-1 RNA levels
• The diagnosis should also be considered in patients being treated for HIV-1 infection, who appear to be virologically suppressed on antiretroviral therapy (ART) but have declining CD4+ T-lymphocyte counts.
• To confirm the diagnosis of HIV-2 infection, use an HIV-1/HIV-2 antibody differentiation immunoassay.
• Quantitative HIV-2 plasma RNA viral load testing is available through select institutions though in patients with HIV-2 infection it is not uncommon for viral loads to be below the limits of detection of the assay.

Management

• Consider consulting an expert in HIV-2 management when starting treatment and selecting a regimen.
• There are no randomized trials that address when to start therapy or what may be an optimal first-line antiretroviral therapy (ART) regimen.
• In general, ART should be offered once HIV-2 infection has been diagnosed and ideally before disease progression. Note that HIV-2 has a drug susceptibility profile that is distinct from HIV-1.
  • Preferred initial ART regimens contain 2 nucleoside reverse transcriptase inhibitors (NRTIs) plus an integrase strand transfer inhibitor (Strong recommendation).
  • Alternative regimens contain 2 NRTIs plus a boosted protease inhibitor active against HIV-2 (Weak recommendation).
  • HIV-2 is intrinsically resistant to nonnucleoside reverse transcriptase inhibitors (NNRTIs) and enfuvirtide.
• During treatment, the HIV-2 plasma RNA level and CD4 T-lymphocyte counts should be routinely monitored (Strong recommendation).
• In the event of treatment failure, consult an expert to help select a second-line regimen as HIV-2 antiretroviral (ARV) resistance testing is not available for clinical use.